1. Field of the Invention
The present invention relates to meteorological instruments, and particularly to a rain gauge with a particulate separator for removing sand, dust and other environmental particulate matter.
2. Description of the Related Art
FIGS. 2-9 illustrate a typical prior art balance-type precipitation gauge. Referring to FIGS. 2 and 4, the housing 9 includes a rain-collecting funnel 10, which is covered by a gauze filter 11 that is positioned across a discharge outlet 12 to prevent the entry or passage of insects or other foreign matter into a recording mechanism mounted within the housing 9. The funnel 10 is provided with a nozzle or spout 13 connected to a nozzle director 14 carried on a support frame 15. The support frame 15 is mounted within the housing 9 and serves to support the recording mechanism.
The support frame 15 includes a vertically disposed plate, which is held within the housing 9 by spaced side guides 16, each guide 16 being fixed to the inner wall of the housing 9. Pivotally mounted to the support frame 15 beneath the spout 13 is a pair of buckets 17, 17a, which have a triangular cross-sectional configuration. The buckets 17, 17a are symmetrically formed and have identical configurations, dimensions, and volumes. The buckets 17, 17a share a common bifurcated partition wall 18, between which a pivot 19 is mounted.
Stop screws 20 are mounted on the frame 15 below the buckets 17, 17a and are arranged to limit the pivotal tilting movements of the buckets (e.g., as shown in FIG. 4, with the buckets 17, 17a in this example tilting towards the right in the Figure). In the example of FIG. 4, the bucket 17, upon receiving a predetermined amount of rainwater from collection funnel 10, causes both buckets 17, 17a to tilt (to the right in FIG. 4) about the pivot 19, allowing the contents of the bucket 17 to be discharged, and further allowing the other bucket 17a to be properly positioned to receive an equal amount of rainwater. The back-and-forth tilting of the buckets, from receiving to discharging positions, continues as long as the rainwater is delivered from the funnel 10 through the spout 13.
In order to adjust the tilting movement of the buckets 17, 17a so that equal amounts of rainwater will be delivered by each bucket, the stop screws 20, as shown in FIG. 6, are provided with conical heads 21 adapted to contact the base sides 22 of the buckets 17, 17a. The base sides 22 of the buckets 17, 17a are angled to form a gutter so that all of the rainwater received in the buckets 17, 17a is discharged when each bucket assumes the tilted or inclined position. The buckets 17, 17a each discharge their contents into respective arms 23, 24 of a Y-shaped collection chute 25 having a discharge nozzle 26. The buckets 17, 17a and the collection chute 25 form a metering device so that, despite the amount of rain water being delivered through the spout 13, equal and constant amounts of water are discharged by the buckets 17, 17a through the nozzle 26 of the chute 25.
The nozzle 26 delivers the rain water alternately into a second pair of pivotally mounted measuring containers in the form of buckets 27, 27a, which are of larger capacity than buckets 17, 17a, but being of the same construction; i.e., having triangular cross-sectional configurations and equal capacities with respect to one another, and also sharing a common bifurcated partition wall 28, between which a pivot 29 for the buckets 27, 27a passes.
A stud 30 is fixed at the rear of the measuring buckets 27, 27a. The stud 30 extends through an arcuate slot 32 in the support frame 15. The stud 30 contacts adjustable screw stops 33 (shown in FIG. 5), which are adapted to enable the tilting movements of the buckets 27, 27a to be accurately adjusted to ensure that each bucket 27, 27a, upon receiving a predetermined volume of water, will tilt to a discharge position and position the other bucket to a receiving position below the nozzle 26.
Each bucket 27, 27a discharges its contents into a respective discharge pipe 34 located in the bottom of the housing 9. Each discharge pipe 34 is covered by gauze 35 to prevent the entry of insects and foreign matter into the housing 9. Secured to the stud 30 is a permanent magnet 36, which, as it moves during tilting movements of the buckets 27, 27a, passes a mercury magnetic switch 37, which is supported by a clamp 38 on the support frame 15. The mercury switch 37 is located centrally with respect to the arcuate movement of the magnet 36 so that, upon each oscillation of the magnet 36 responsive to the buckets 27, 27a filling and discharging, the switch 37 is actuated to close a circuit, which energizes an electric impulse recording counter 39 (shown in FIG. 3), which is also mounted on the frame 15. The counter 39 has a numeral indicating end 40 positioned to be visible through an inspection window 41 in the wall of the housing 9. The counter 39 may be any suitable type of counter, such as the typical four FIG. 6-V-Ohm counter known in the field of telephones.
FIG. 9 illustrates a circuit for energizing the counter 39, in which a battery 42, supported in brackets 43 on the frame 15, is connected in series with a main control switch 44, the mercury switch 37, and the counter 39. Connected in parallel with the counter 39 is a plug 45, enabling the circuit to be connected to an indicator or recording device (not shown) at a base station. The plug 45 may be connected with a socket 46 mounted in the sidewall of housing 9 for connection to a landline (not shown), which connects the counter 39 with the remote indicator or recorder, and which will be energized simultaneously with the counter 39.
In operation, when rainwater is collected in the funnel 10, it is then passed through the nozzle 13 into the uppermost of buckets 17, 17a. Due to the configuration of the buckets 17, 17a and the pivotal mounting, the addition of the rainwater causes instability. When a predetermined amount of rainwater is received, the bucket 17, 17a will tilt about the pivot 19 until it reaches one of the stop screws 20. At this point, the rainwater is discharged into the collection chute 25, and the other bucket 17, 7a begins to fill with rainwater, and the process then repeats itself.
The water delivered from the buckets 17, 17a is discharged through the nozzle 26, in the same manner, alternately filling the measuring buckets 27, 27a, which, during each oscillation, causes the counter 39 to energize through the magnetic mercury switch 37. If the buckets 27, 27a have been calibrated to hold a certain volume of water before each bucket 27, 27a moves to the discharge position, a reading of the number of full buckets will give a reading of the amount of water collected by the precipitation gauge, which can be calibrated to give a reading of the actual rainfall at the location where the gauge is located.
The coarse calibration is effected by making the buckets 27, 27a the size that is necessary, and the fine calibration is effected by adjusting the positions of the stop screws 33 on the frame 15 and arranged to contact the stud 30 on the buckets 27, 27a so that each bucket 27, 27a tips from one position to the other when the amount of water in either is set to a desired measurement, such as one point of rain.
An example of such a typical prior art precipitation gauge is shown in U.S. Pat. No. 3,243,999, which is hereby incorporated by reference in its entirety. Due to the use of two sets of buckets (i.e., 17, 17a and 27, 27a), rather than a single set of buckets, that are used solely for the measuring process, the above system requires dual calibration and the possibility of mechanical failure, misalignment and necessary maintenance becomes doubled. Additionally, due to the use of gauze to prevent contamination by insects and other foreign matter, the gauze screen must be constantly changed, given that it will become permanently soiled and clogged with each rainfall.
Thus, a rain gauge with a particulate separator solving the aforementioned problems is desired.